In Batman, the known unknowns provide plenty of uncertainty

Malcolm Turnbull is correct: Bill Shorten is lurching leftwards for the 17 March Batman by-election. The Labor leader’s fiery National Press Club speech was all about economic equality and action on the environment, and since then he has gone further, backtracking on support for Queensland’s contentious Adani mine.

As a rule, by-elections attract scrutiny far out of proportion to their importance, but this is different. Under normal circumstances, a seat changing hands from one major party to the other can be expected to return to roughly its natural position on the pendulum at the next general election. (Recall Ryan in Queensland, snatched by Labor in March 2001 and returned to the Liberals in November.)

But losing to a third party is more serious, because regaining that spot in parliament can prove all but impossible. The Nationals can attest to the particular tendency of rural independents to dig in. The ebbs and flows of national two-party electoral cycles simply don’t apply.